🔍 Key Concepts

• Screen tubes location and purpose in a water‑tube boiler (what they protect, where they sit in relation to the furnace and superheater) • Difference between a drum (steam drum, water/mud drum) and a header in boiler construction • Flow path of water/steam from the lower drum up through generating tubes, screen tubes, and into the upper drum

💭 Think About

• On the illustration, identify which group of tubes is labeled as the screen tubes and visually trace where each end of those tubes terminates. • Ask yourself: do the screen tubes connect directly into a drum, or do they connect into a front header that itself is piped to the drum? • Consider which connection arrangement would best allow the screen tubes to receive relatively cooler water from below and discharge hotter mixture/steam to the upper regions of the boiler.

✅ Before You Answer

• Verify on the drawing which component is explicitly marked as the steam drum and which is the water (or mud) drum. • Confirm whether the ends of the screen tubes appear to enter a front header box or go straight into a drum shell. • Make sure your chosen option reflects the actual physical connection you can see in the illustration, not just a typical textbook description of screen tubes.